The present invention pertains to a tag conversion apparatus.
In constructing a network such as a datacenter and the like, IEEE802.1Q (VLAN (Virtual Local Area Network) tagging) has been used for separating networks virtually for customers. However, in recent years, the required number of separable networks has been increasing and it has become a problem that the separable number of 4094 by VLAN tagging is insufficient.
Thus, double VLAN tagging is standardized in IEEE802.1ad. Double VLAN tagging employs the double tag configuration using two types of VLAN tags. One type of VLAN tag is called C-tag (Customer tag) and the other type of VLAN tag is called S-tag (Service tag).
For example, C-tags are used for a datacenter business operator to separate networks and S-tags are used for a communication carrier connecting datacenters to separate the datacenter business operators. Double VLAN tagging allows a datacenter business operator to separate networks of the datacenter and, simultaneously, for a communication carrier to separate datacenter business operators. Double VLAN tagging is capable of separate approximately 160,000 (4094*4094) networks as a whole.
Further, VXLAN (Virtual eXtensible Local Area Network) tagging is proposed. VXLAN tagging encapsulates a customer frame using VXLAN tag to increase the maximum number of separable networks.
A VXLAN tag mainly consists of a UDP/IP header and a network separation identifier (24 bits) capable of separating approximately 160,000 networks. Compared with IEEE802.ad, VXLAN tagging has a single tag configuration. A customer frame encapsulated with a VXLAN tag may further contains a VLAN tag. This frame configuration is a double tag configuration with a VXLAN tag and a VLAN tag.
Further, U.S. Pat. No. 8,223,770B2 discloses the following network configuration (see abstract). “A virtual network has virtual machines on physical devices connected to network interfaces each coupled by tunnels through a forwarding network, each interface having a forwarding address in an address space of the forwarding network, each network interface having a reconfigurable address mapper for determining a forwarding address for a packet, and encapsulating the packet with its forwarding address so that the forwarding network can deliver the data packet to the remote physical device having that forwarding address.”